1. Field of the Invention
The present invention relates generally to foot prosthetic devices.
2. Related Art
Many individuals have lost a limb for various reasons including war, accident, or disease. In most instances these individuals are not only able to live relatively normal lives, but physically active lives as well. Often times, these individuals are aided in their everyday lives by a prosthetic limb. The objective of prosthesis is to provide an artificial limb that simulates the function and natural feel of the replaced limb.
With respect to prosthetic feet, the development of a functional and natural artificial foot has been limited only by material and imagination. Many designs have attempted to copy the anatomy of the foot or simulate its actions by replacing the bones and muscle with various mechanical components. Other designs have departed radically from mere anatomical copying or mechanical simulation by replacing the entire foot with an energy storage element, such as a spring. As the user steps onto the foot, the user's weight compresses the spring. As the user moves forward, the user's weight comes off the foot and the energy stored in the spring is used to propel the user forward.
In addition, the performance of these energy storing feet has been altered in various ways, such as by using multiple springs with a primary spring and a secondary spring that deflect at different intervals of foot deflection to add resistance. Unfortunately, such multiple spring feet have not provided the stiff resiliency desired through high load portions of a user's gait while still allowing the foot to have a softer resiliency when the user assumes a terminal stance.